What is StarStream®?

StarStream® is a technology that allows a gentle stream of water to clean very effectively. It is so good that it can usually clean without having to heat the water (which saves energy) and without any additives (which reduces pollution risk and cost).

StarStream’s “party trick” is to demonstrate how well it enhances the cleaning of any given liquid (enhancing cold water by 1000x in industry tests – click here). However, StarStream can be used with other liquids or additives if they need enhancing.

For StarStream developments in the period 2016 ff., please click here.

Early results

Invented and patented by Professor Tim Leighton (ISVR) and Dr Peter Birkin (Chemistry), StarStream quickly showed its ability to clean a variety of targets, as shown in the videos below. Starstream is particularly effective at cleaning out any grooves and cracks in the surfaces, areas that are difficult to reach for conventional cleaning technologies.

In the first few videos, StarStream passes a gentle stream of cold water over the target. After a countdown of 5, 4, 3, 2, 1, StarStream is turned on and bubbles and sound are added to the cold water:

Watch as StarStream revives a woodwind reed that would otherwise be discarded

Current clinical tests

Now StarStream is being used by other NAMRIP members to look at cleaning for dentistry, for cleaning surgical instruments, and many other applications. Click on the ‘publications’ tab to access the formal journal papers on these studies.

Railway cleaning

StarStream® has been tested in two cleaning projects within the railway industry. The first was a quick test on cleaning a clutch spring that had been lubricated with gold grease (very difficult to remove) and then worked under a train for 2 years. It had been removed for cleaning by Faiveley Transport UK who brought it to StarStream to see if it could be cleaned with cold water. Because gold grease is hard to remove, we added surfactant to the spring and cleaned one end of it with StarStream. Click on the video below to see the results.

Even with StarStream, just cold water without additives cannot clean the air intake mesh that has been in service on the front of a train for a long time. However, when domestic detergent is first sprayed on the sensor, although cold water cannot clean the mesh, StarStream can.

StarStream, using just cold water without additives, can clean the surface of a sensor that has been in use for a long time under a train. However, StarStream’s cold water cleaning is made much more rapid when domestic detergent is first sprayed on the sensor.

The other railway project involved trying to remove the slippery paste that forms on railway lines when trains pass over fallen leaves on the line. This paste is extremely difficult to remove, and the slippery rails means trains have to travel more slowly, causing £50 million loss each year. We tested to see if StarStream, using just cold water without surfactant, could remove it (and ultrasonic cleaning bath could not). Click here for details and see the video below.

Pipe and tube cleaning

StarStream can also clean in tubes and pipes. This can range from cm-diameter pipes used for coolant in the power industry, to mm-diameter pipes within endoscopes. In the video below we look at the example of cleaning in pipes used to dispense drinks (e.g. at vending machines) or food (e.g. to fill cartons and pots at a factory). The scenario in question is a food dispenser pipe, just as might be found on drink dispenser machines, or in factories where tubs are filled with yogurt, cream etc. After use, the pipe is filled with old product, which can contaminate the next foodstuff to go through the pipe (e.g. a different drink) or might cause bacterial biofilms to grow in the pipe. If bleach or biocide is pumped through the pipe to avoid this, food product must then be pumped through to remove the bleach, a process which leaves the same problem it was trying to solve. Here, cold water is pumped through the pipe via StarStream (which at first is turned off, and then turned on).

This then raises the question of how far along a pipe can StarStream generate a cleaning effect. Imagine a pub, with beer barrels in the cellar, and pipes going all the way to the taps in the bar. It would be very easy to place StarStream nozzles in that piping, so that when the beer is pumped through it the ultrasound is turned off; but when the line is flushed with just cold water (instead of bleach), the ultrasound is turned on to clean it. How far apart would we need to place the StarStream nozzles to clean the pipe? In the video below, we test whether StarStream can clean 30 cm along a pipe:

Handwashing

We are trying to get funding for a dedicated trial to test the ability of StarStream to clean hands without damaging tissue. We have some evidence that StartStream might be good at hand cleaning, including the skin cleaning (pig skin and rubber mimic skin) tests in the papers found here and here, and the evidence in the following videos:

The Centre for Disease Control recommends that people wash their hands for 20 s in warm soapy water. The average for the UK is 6 s, often in cold water without soap. We have tried to change behaviour for handwashing but cannot, so let us change the water so that those 6 s in cold water are as effective as 20 s in warm soapy water. In hospitals you might say handwashing is covered by alcohol rubs, but that is thinking too small – just on the topic of AntiMicrobial Resistance (AMR), we cannot just think in terms of the hospital setting – we need better washing, including handwashing on farms, abattoirs, kitchens, butchers, on cruise ships and aircraft, and indeed across society. If we do not have an approach to AMR across society (including beyond the healthcare setting), then by 2050 it will kill more people than cancer and cost the global economy more that the size of the current global economy.

Impact: Getting it out there

However, inventions like this will stay on the lab bench, helping no-one, unless we can make a business that will sell 50,000 at prices the NHS and Local Authorities are prepared to pay. We need to build a business. StarStream developed through early prototypes to the point where it was licensed to Ultrawave Ltd. for manufacturing.

How does it work?

The video below (from a science show in Germany) shows an animation of how the device adds sound and bubbles to a water stream to make it work (the animation starts at 3 mins 30 s into the clip). The show is German National Public Broadcast TV, “Die Grosse Show der Naturwunder”, Episode 21, ARD, (15 August 2013; Germany’s top TV science show).

What are the advantages of StarStream?

Potential to reduce the volume of water consumed – this not only saves on a scarce resource, but means that less contaminated run-off is produced (which in third world countries can contaminate water supplies).

Although StarStream can clean with any liquid, and heated liquid, if all you have is cold water or saline, then StarStream can clean with that. Imagine if every emergency vehicle, rescue boat or army medic were equipped with a small cylinder of saline (like a small fire extinguisher) with a StarStream nozzle on the top and a battery (such as found in hand-held vacuum cleaners): A wound could be cleaned on site before transport to hospital. If a wound is simply packed, blood poisoning can set in during transport to hospital. In Iraq and Afghanistan, it often takes 30-90 minutes for wounded troops to reach a Level II (damage control and stabilization) facility or a Level 3 (repair) hospital facility. As drug-resistant strains of microbes becomes increasingly prevalent, wound cleaning becomes ever more important. In the Vietnam War, sepsis was the third leading cause of death amongst US troops for combat casualties in action.

Could reduce the energy normally required to heat the water usually used to clean surfaces (so saving on the energy costs and carbon footprint).

Uses minimal additives (so making subsequent treatment of the water less costly, and reducing the contamination risk from run-off).

In comparison to power/pressure washers, it produces far less aerosol and therefore reduces the risk of secondary contamination through droplets. Important potential applications are in the nuclear industry, and biomedical labs. The ability to clean without producing significant aerosols or 'splash-back' allows the technology to be deployed for 'clean in place' applications where conventional techniques are either too dangerous (to personnel or the environment) or not practical. This ability represents huge commercial benefits through the reduction in down time caused by the current need to remove or dismantle contaminated equipment in order to allow it to be cleaned.

As a replacement for the ultrasonic cleaning bath, so that the object to be cleaned does not sit in a ‘soup’ of contaminated liquid (particularly important for biomedical contaminations) but instead can be cleaned and rinsed simultaneously. The US Government has been successfully sued by veterans who acquired serious infections from routine colonoscopies. With increasing numbers of endoscopy procedures and limited time available to clean instruments between each, such cases are likely to increase worldwide if the technologies do not improve. This is particularly important given the resistance of some microorganisms and prions such as those responsible for CJD. Cleaning baths are restricted to those items small enough to fit in them, and do not clean uniformly but have ‘hot spots’ and ‘cold spots’ (there being negligible cleaning at the latter). In StarStream the liquid stream can be passed over the item ensuring uniform cleaning is achieved on the treated area.

Applications

1. Where chemical-free cleaning is required

Chemical-free cleaning

In pipes and tubes for producing or dispensing beverages and food product. When detergents are used to clean such pipes, they spoil the taste of the next batch of product. Currently, after pipes are cleaned with chemicals, beverage and food product is wasted in flushing out the detergent. With StarStream, water without additives can be used for cleaning. Click here.

Other examples: contact lenses, baby pacifiers and feeding bottles.

2. When the weight of water means only limited amounts can be carried, but electrical power is available

Emergency vehicles

In ambulances and emergency vehicles for wound cleaning with saline-equipped StarStream.

Cruise liner

On planes and cruise liners, where hand hygiene is critical, given proximity of food, toilets and crowded conditions.

On small boats, where freshwater is limited.

Fire-fighter

A battery-powered 3 minute wound/skin wash by a ‘fire-extinguisher-type’ saline-equipped StarStream, for army medics, firemen, first responders, and in the chemical, nuclear and petrochemical industries.

Meat

3. When chemicals alone are too slow to penetrate pores by diffusion, and StarStream can drag chemicals into pores in the bubble wake

4. In providing a quick, easy-to-use pre-clean to prevent later cleaning processes receiving dried-on material, or clumped contaminant where the outer layers protect the inner

Tool

Cleaning surgical instruments immediately after use, before transportation to Sterile Services facilities (which might be closed at the weekend).

5. Where ‘clean-in-place’ systems are required, because objects are too large to fit in cleaning baths, or too costly to dismantle

Indoors

Cleaning vehicles, industrial plants etc., especially where this is indoors such that pressure washers cannot be used.

Simple to use

StarStream was designed to ‘clean in place’ – an item does not need to be disassembled, as large items must be to fit in ultrasonic cleaning baths; and you can take the cleaner to the item to be cleaned because StarStream just fits on the end of a normal hose or tap. It is very easy to use with minimal training, and can run off cold tap water without additives – so it is just ‘plug and play’.

A quick rinse

Because it requires little training and runs without special facilities (just mains tap water and normal household electricity supply), it could provide a ‘quick rinse’ of a number of items, for example the tools at the end of a duodenoscope, to remove the bulk of tissue clumps. This might become increasingly important as the economic recession causes more Sterile Services departments to close at weekends. If tools used on Friday afternoon are allowed to dry all weekend before attempts are made to clean them on a Monday, the hazard of infecting the next patient increases greatly (the brain protein was in fact allowed to dry for 24 hours before cleaning by StarStream in the tests in the video found by clicking here and the brain protein tests in the paper found by clicking here). Even if instruments are kept moist, when tissue clumps it becomes difficult to clean, and StarStream is effective at breaking up clumps. In a great many scenarios, a quick StarStream rinse immediately after use will reduce the risk of infection by ensuring that subsequent cleaning technologies have only a fraction of a percentage of the original material remaining for them to deal with. Stories of infections via a range of agents transmitted through dental, endoscopic, colonoscopic and duodenoscopic procedures continue to feature in the press, examples of which can be found in USA Today , CNN , Seattle PI , Health News Digest and the Department of Veterans , whilst in the UK there is renewed concerned regarding CJD in cattle.

What can StarStream do?

The range of contaminants that it removes with just cold water is large (see the videos found by clicking here ) although if necessary the water can be heated and additives (bleach, detergent, biocide etc.) could be added. Further tests in the field setting are needed to see what is necessary for the contamination in question.

StarStream cleans by a mechanical scrubbing action, which is very different to the chemical attacks that microbes are often challenged with, so giving another route to combat AntiMicrobial Resistance (AMR). It is estimated that by 2050, unless AMR is tackle, it will kill more people than cancer and cost the global economy more than the size of the current economy. It occurs because bacteria, fungi, viruses and other microbes develop resistance to antimicrobial agents. A major problem is that such agents enter the environment (the water supply, sewage, run-off etc.) where their occurrence aids the development of AMR. With StarStream, not only can we clean well, but nothing enters the run off except the material we clean off – there are no chemical clues that are flushed into the environment that microbe populations can use in the development of AMR.

How is it that StarStream cleans crevices well?

Cracks, crevices, contoured surfaces and intricate architectures (like small tools) are usually difficult to clean because (i) brushes and wipes do not penetrate these architectures well and (ii) any chemicals (such as biocides) often do not penetrate them well, e.g. often relying on passive diffusion to penetrate crevices.

StarStream is very good at cleaning in cracks and crevices, because the interaction of the crevice with the sound field creates an ‘acoustic radiation force’, which actively draws bubbles into the crevices. These bubbles are shimmering, their walls rippling at high speed and creating shear, as shown in the panel below:

A bubble micro-scrubber

(See also the BBC footage here to see these ripples and shear). Hence the bubbles are like microscopic scrubbing machines, removing contaminants from surfaces. The ‘acoustic radiation forces’ make the bubbles seek out crevices, burrow into them, and clean them. In this way we have been able to clean using just cold tap water – cleaning with cold tap water, without any additives, is StarStream’s “party trick”. However, if you do wish to add chemicals such as a bleach or biocide, StarStream helps these chemicals penetrate cracks and crevices much more quickly than mere passive diffusion would allow. Chemicals are dragged in the wake of the bubble as it enters the crevice, and so are pulled into the crevice. Therefore, StarStream does three things:

(a) Bubbles act as microscopic scrubbing machines

(b) Bubbles actively seek out the cracks, crevices, and contoured architecture that is usually so difficult to clean

(c) If chemicals are added to the liquid, StarStream drags them into the cracks and crevices much more quickly, and to much higher concentrations, than would occur without StarStream.

Other configurations

Currently StarStream is built into a hairdryer-type device for manual cleaning, but could be fixed onto robot arms for other applications, e.g. producing arrays of cleaners that can access hard-to-reach areas.

The ability of StarStream to clean with a simple-to-use rinse does not only apply to instruments. Battlefield wounds can be extremely dirty, and blood poisoning can set in during transportation of the victim to hospital. In recent combat zones, water has been scarce and hospitals an hour or more distant. Saline and rinse fluids are heavy for army medics, but a small amount of saline/rinse, in a ‘fire extinguisher’-type cylinder with a battery-powered StarStream nozzle, could clean the wound before transport. Ambulances, rescue vehicles, small boats, helicopters etc. could all carry such items.

Media coverage for StarStream

The stages in the investigations into StarStream are outlined below in third-party items in the media:

Acknowledgements: Parts of this work were funded by the 2011 Royal Society Brian Mercer Award for Innovation. The research team were Leighton, T.G., (Principal Investigator; ISVR, Engineering & the Environment); Birkin, P., Offin D., Vian C. (Chemistry); Howlin, R., Stoodley, P. (nCATS, Engineering & the Environment); Secker, T., Herve, R., Keevil, B. (Centre for Biological Sciences); Dawson, J. I., Oreffo, R. O. C. (Centre for Human Development, Stem Cells and Regeneration, Medicine); Banda, N. and Jiang., J. (ISVR, Engineering & the Environment). Other elements of the work were funded by Prof Leighton’s consultancy activities. Dstl funded some of the early stages of the work and Ultrawave Ltd provided support in prototype construction and had recently funded a PhD studentship, and TGL is very grateful for their fruitful collaboration.